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Paul

This is the focused model discussion - please only post about the model output. 

For a more laid back, bantery model discussion please use the Cold hunt - models and banter thread.

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6 minutes ago, Sperrin said:

Would @bluearmy or anyone else have time to give a quick explanation of a wedge? Am I right in thinking its an increase in application of a high pressure cell that causes the jet to come in on a NW/SE axis causing a PM flow as opposed to full on Greenland block?

A wedge of heights to the N or NE of the UK that can direct low pressure system on a more SE trajectory in a sliding fashion over the UK! Is my understanding. 

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1 hour ago, karlos1983 said:

A wedge of heights to the N or NE of the UK that can direct low pressure system on a more SE trajectory in a sliding fashion over the UK! Is my understanding. 

https://www.google.com/search?q=in+meteorology+what+is+a+wedge%3F&rls=com.microsoft:en-GB:IE-Address&ie=UTF-8&oe=UTF-8&sourceid=ie7&gws_rd=ssl

various links but all say ridge of high pressure

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11 minutes ago, johnholmes said:

Yes exactly John. But I think when we use the term it’s usually to our N or NE forcing sliding lows over the uk and bringing snow chances. Obviously wedges of heights could appear anywhere on the globe, but this is usually when many would refer to said wedges on this forum... I think 😀

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1 hour ago, Sperrin said:

Would @bluearmy or anyone else have time to give a quick explanation of a wedge? Am I right in thinking its an increase in application of a high pressure cell that causes the jet to come in on a NW/SE axis causing a PM flow as opposed to full on Greenland block?

 

 

 

1 hour ago, karlos1983 said:

A wedge of heights to the N or NE of the UK that can direct low pressure system on a more SE trajectory in a sliding fashion over the UK! Is my understanding. 

 

 

 

23 minutes ago, johnholmes said:

 

 

 

9 minutes ago, karlos1983 said:

Yes exactly John. But I think when we use the term it’s usually to our N or NE forcing sliding lows over the uk and bringing snow chances. Obviously wedges of heights could appear anywhere on the globe, but this is usually when many would refer to said wedges on this forum... I think 😀

 

Something along these lines from Jan. 2013 ,a pattern not dis-similar to our current one but with that one notable difference to our ne.


gfsnh-2013011700-0-48.thumb.png.fb9b052803f7a07f9d431364a25a9d77.pnggfs-2013011700-2-48.thumb.png.094de84327e2c5c86234206ccf37e3a4.png

As karlos said we see the jet forced se like now but with that "wedge" of heights like an island within a vast area of low heights across the pole.This is the difference to now  because Atlantic fronts bringing the rain turns to snow as it reaches the uk because the flow is backing and bringing continental air from the se with lower dew points.

We live in hope that if the Canadian vortex backs off a bit then we get something like this in our current pattern.

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30 minutes ago, johnholmes said:

To me a wedge is a door wedge shaped ridge pointing towards the polar regions as we see it on the actual weather map, any high pressure is a ridge, if you think of it in 3D, looking from a height, as the heights will be higher relative to the air surrounding it, best way to think of it is like oceanic waves, except within the Atmosphere - thats my take anyway.

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I'm sorry but this to me this is the subtropical anticyclone ridging north within the fluid movement of the warm/cold, air with the trough being driven south east by the jet, I leave the wedges to McCains

gfs_z500a_natl_10.thumb.png.116f407fc5825a2987d47081443bf7ab.png

Edited by knocker
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Hi guys, thanks for your help. Much clearer now. 👍

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30 minutes ago, knocker said:

I'm sorry but this to me this is the subtropical anticyclone ridging north within the fluid movement of the warm/cold, air with the trough being driven south east by the jet, I leave the wedges to McCains

gfs_z500a_natl_10.thumb.png.116f407fc5825a2987d47081443bf7ab.png

True that 'wedges' often come and go much as they do on people's dinner plates, what people are considering (whether they realise it or not) is one that has some stratospheric support which enables it to stick around for a few days. That being what took place in Jan 2013.

If we're going to see such a thing then it'll likely turn up at less than a week's notice, as the relatively localised strat-trop connection is a tough one for numerical modelling to resolve.

 

@Nick F, that's a nice spot regarding the downwelling - the models have mostly been hesitant with it bar the odd run finding a much quicker route. There was for some time much expectation of a landing point around 22nd but this was based on the 'average' downwelling time for diffuse events; about 15 days from the initial split. EPS spent a while indicating that this may prove accurate but sadly this hasn't been the case and we're now looking toward the most lagged outcomes in observed history; some 25 days from initial split. Hard to believe it could lag much beyond that, but today's model trends give cause to wonder if we're in uncharted territory.

Also I should clarify; I'm referring to some significant downwelling on a regional scale to begin with; the most widespread impacts can have much greater lag; up to 60 days like we saw in 2013.

Edited by Singularity
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Unfortunately re strat the Canadian vortex has restrengthened at 50hPa day 10 on Berlin. Not what we wanted to see

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36 minutes ago, knocker said:

I'm sorry but this to me this is the subtropical anticyclone ridging north within the fluid movement of the warm/cold, air with the trough being driven south east by the jet, I leave the wedges to McCains

gfs_z500a_natl_10.thumb.png.116f407fc5825a2987d47081443bf7ab.png

It is - that’s why we don’t get a wedge and the trough topples into nw Europe 

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3 minutes ago, chionomaniac said:

Unfortunately re strat the Canadian vortex has restrengthened at 50hPa day 10 on Berlin. Not what we wanted to see

Hmm - that seems implausibly fast to be via the upper stratosphere though, could be a fluctuation from below?

Regardless, it's a good job the MJO projections have improved today with respect to taking it into phases that should help take down the Azores High and allow more of a 'runners into the base of a cold trough' type pattern to develop for the UK. That's the one way that the Canadian vortex staying stronger could be used in our favour, provided we see enough counter-zonal forcing near-NW or N of the UK... both the stratosphere and tropical forcing are capable of supplying this so you never know, we could do quite well for widespread snowfall, albeit tending to favour high ground more often than many would like.

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Just now, Singularity said:

Hmm - that seems implausibly fast to be via the upper stratosphere though, could be a fluctuation from below?

Regardless, it's a good job the MJO projections have improved today with respect to taking it into phases that should help take down the Azores High and allow more of a 'runners into the base of a cold trough' type pattern to develop for the UK. That's the one way that the Canadian vortex staying stronger could be used in our favour, provided we see enough counter-zonal forcing near-NW or N of the UK... both the stratosphere and tropical forcing are capable of supplying this so you never know, we could do quite well for widespread snowfall, albeit tending to favour high ground more often than many would like.

Yes, more than likely

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9 minutes ago, chionomaniac said:

Unfortunately re strat the Canadian vortex has restrengthened at 50hPa day 10 on Berlin. Not what we wanted to see

Next run at same timescale ed

4262ADBF-CCEE-4875-9A1A-41346C7F5AFC.thumb.jpeg.999080341741f66cf007500832430bc9.jpeg

Splits at day 10

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2 minutes ago, chionomaniac said:

Yes, more than likely

Spotted this myself. If it's not too progressive I'm ready to call time on significant SSW impacts for this side of the hemisphere 

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The gfs steady as a rock Anyway I'm still mulling over Chio's use of the majestic plural pronoun

2019012106_f192_50.nonenonehghtnonebrbk_nhem.gfs003.thumb.gif.8caa831ce272c4dc1b4167cab045c1d0.gif

Edited by knocker
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9 minutes ago, bluearmy said:

Next run at same timescale ed

4262ADBF-CCEE-4875-9A1A-41346C7F5AFC.thumb.jpeg.999080341741f66cf007500832430bc9.jpeg

Splits at day 10

You would think that that type of pattern would be highly beneficial for us! We just need the Cancian segment to nudge a bit more west.....

Edited by chionomaniac
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Quite a few of the 00z ops were playing with an upper scrussian ridge as we go into week 2 .... updated ukmo also now on that page ..... seems a logical consequence of the strong  jet on a nw/we axis and surely plays into the possible slider scenario ...  - the wedge chart from 2013 posted above .... we could develop an upper ridge in that area from a scrussian opening .....

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If someone can post a gif of the gem NH profile from day 7 to 10 I think you will find it very revealing ......classic downwelling wave imo as the purples lighten to blue across a swathe of the NH .... may not be right btw !

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anim_sof8.gif

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22 minutes ago, bluearmy said:

Quite a few of the 00z ops were playing with an upper scrussian ridge as we go into week 2 .... updated ukmo also now on that page ..... seems a logical consequence of the strong  jet on a nw/we axis and surely plays into the possible slider scenario ...  - the wedge chart from 2013 posted above .... we could develop an upper ridge in that area from a scrussian opening .....

Was about to post something similar, Nick. I guess looking at the NW/SE jet axis alongside the 50hPa profile then the logical area for any block to appear is from Russia to Scandinavia. Whether it will be too far NE remains to be seen.

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30 minutes ago, bluearmy said:

Quite a few of the 00z ops were playing with an upper scrussian ridge as we go into week 2 .... updated ukmo also now on that page ..... seems a logical consequence of the strong  jet on a nw/we axis and surely plays into the possible slider scenario ...  - the wedge chart from 2013 posted above .... we could develop an upper ridge in that area from a scrussian opening .....

I did post earlier that could be the trend.No point re posting GEFS as they will update soon.

image.thumb.png.2c0e4e0fd8fc1aee57e4c9b2d7c95b18.pngUKMO

image.thumb.png.5b01da5a3ff1ba9978de58f45233be21.pngGEM

Edited by winterof79

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2 minutes ago, winterof79 said:

I did post earlier that could be the trend 

UKMO

GEM

 

2 minutes ago, chionomaniac said:

Was about to post something similar, Nick. I guess looking at the NW/SE jet axis alongside the 50hPa profile then the logical area for any block to appear is from Russia to Scandinavia. Whether it will be too far NE remains to be seen.

If gem is onto something then it probably wouldn’t matter !  Either way it shouldn’t be quiet in here going forward ......

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6 minutes ago, chionomaniac said:

Was about to post something similar, Nick. I guess looking at the NW/SE jet axis alongside the 50hPa profile then the logical area for any block to appear is from Russia to Scandinavia. Whether it will be too far NE remains to be seen.

 

2 minutes ago, bluearmy said:

 

If gem is onto something then it probably wouldn’t matter !  Either way it shouldn’t be quiet in here going forward ......

Lol just like this Nick - too far NE!

D1E56133-0627-4943-A060-FA057D0EC39E.thumb.jpeg.8346fe1715ab54a43f0b0c62d016439e.jpeg

 

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11 minutes ago, bluearmy said:

 

If gem is onto something then it probably wouldn’t matter !  Either way it shouldn’t be quiet in here going forward ......

FI but you get what I mean. We have been wedged.

 

Posted in wrong order so numbered sequence

 

 

 

image.png3

image.png1

image.png2

Edited by winterof79
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